| The concrete-filled steel tube (CFST) column system has been widely used in industry workshop, high-level architecture and other structures, because it has many advantages, such as high capacity, construction efficiency, fire resistance, simply connections and ecology. Frame node, as the hinge of force transferring, should have enough strength and necessary ductility. In this paper, a new type of reinforced concrete beam-concrete filled steel tube column joint has been proposed, which can improve the bending and shear capacity of connection with steel corbel and steel reinforced concrete (SRC) ring beam. The main works of this paper are as follows:1. Based on the current interrelated national codes and standards, ten1/4scale connection specimens were manufactured. The seismic behaviors of the connections were analyzed through cyclic loading tests. And parametric analyses were also conduced on the specimens, such as steel corbels length, ring beam section size, steel bar connection mode and the axial compression ratio of column etc. The experimental results show that to this type of connection has the feature of clear force transfer mechanism and good seismic behavior. The steel bar lapping on the flange of steel corbels can meet the seismic requirements. And the parameters of the steel corbels length, ring beam section size, the axial compression ratio of column et. al have some influence on the seismic behavior of connects.2. Finite element analysis of the ten scale specimens using software ABAOUS were carried out. The numerical analysis results were in good agreement with that of experiment. Then some parameters were discussed based on the verified finite element model, including the length of steel corbels, steel bar diameter of RC frame beam, thickness of the steel tube, strength of the filled concrete, steel bar of ring beam et. al. The results show that the length of steel corbels and steel bar diameter of RC frame beam have great influence on the skeleton curve of finite element models, and thickness of the steel tube, strength of the filled concrete, steel bar of ring beam have little influence on the mechanical properties of connections.3. Through the nonlinear regression analysis, a restoring force model of this new type of RC beam-CFST column joint was set up, which a three linear model is considering the yield load, ultimate load and stiffness degradation of failure load. And the results of restoring force model agree well with tested and calculated result. The model can be applied to the elastic-plastic problems in dynamic analysis of structure.4. Based on the results of experiment and numerical analysis, the theoretical calculation model of the type of RC beam-CFST column connection to estimate the moment force and shear force transfer mechanism were presented according the theory of plastic limit equilibrium, and the formulas of the joint moment capacity and shear capacity were obtained. The results can provide some references in the actual project design of this type connection.5.2bays,7stories frame model with CFST column-RC beam structural system is designed and manufactured. The model is one tenth of the real structure. Then the modal parameters of the models with/without lateral bracings are identified including natural frequency, damping ratio and mode shape by the experimental modal analysis. And the experimental research on its seismic response is carried out through shaking table test method. The experimental results show that the first modes of the two systems with/without lateral bracings all appear on the plane with little stiffness. During the experiment, the model is always in the elastic range and has good ductility, which indicates that this kind of structure possess excellent seismic behaviors. |
PDF Full Text Request